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Development of the electrophoretic method for determination of phosphates and borates in cooling mixtures
Listakhava, Iryna ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
In this diploma thesis, a method of routine analysis of commercial coolants was developed, focused on the simultaneous determination of inorganic anions - phosphates and borates - as corrosion inhibitors in fresh mixtures and the markers of recycling quality. The method was developed for the instrumental technique of capillary zone electrophoresis with indirect detection at 254 nm. The following were optimized: background electrolyte (its composition, concentration, pH), measured samples (coolant dilution, suitable internal standard) and measurement conditions (capillary length, sample dosing). The influence of the sample matrix on the measurement results, the robustness of the calibration line (or the agreement of the response with the actual analyte concentration) and also the repeatability of the method were tested. Optimizations and tests resulted in a method based on a standard addition with the following parameters: background electrolyte of pH = 11.50 containing sodium chromate at 10 mmol l-1 concentration and CTAB at 1 mmol l-1 concentration; dilution of the coolant sample 20-50×, addition of internal standard MES at 0,1 mmol l-1 concentration, electrokinetic sample injection at -5 kV for 10 s, capillary length 50.0 cm, inner diameter 75 μm. The repeatability of the method expressed as a...
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